38 CONCHOLOGY. 



and oblique aperture anteriorly ; posterior extremity nearly closed 

 hinge linear ; marginal and without teeth. Three species. 

 Gastrocheena cuneiformis. Gastrochsena mytiloides. 



G. modiolina. 



FAMILY III. 



SoLEXEA. Four genera. 

 1. Genus Solen. PI. VI. 



minimal. Body cylindroid, much elongated ; the mantle in 

 form of a canal open at both ends, closed in the rest of its extent 

 by a thick epidermis which surrounds it ; a cylindroid anterior 

 foot. 



Shell. Equivalve, extremely inequilateral, the summits very 

 small, and entirely at the commencement of the dorsal line ; one 

 or two teeth in the hinge. Inhabits the seas of America and Eu- 

 rope. Twenty-one species. 



Solen vaginus. Solen antiquatus. 



S. corneus. S. vaginoides. 



S. pygmseus. S. siliqua. 



S. ambiguus, S. cultellus. 



S. Dombeii. S. planus. 



S. Javanicus. S. constrictus. 



S. Caribaeus. S. coarctatus. 



S. violaceus. 



S. ensis.* S. centralis.* 



S. minutus.* S. rostratus.* 



S. viridis.* S. giganteus.* 



2. Genus Fanopsea. PI. VI. 



Animal. Unknown. 



The situation of the ligament, and the prominency of the 

 apex, are the characters which distinguish it from the Mya. 



Shell. Regular oval, elongated, gaping at both ends, equivalve, 

 inequilateral ; summit little marked and anterodorsal ; hinge com- 



